Greatest Mysteries: How Did Human Culture Evolve?

Editor's Note:We asked several scientists from various fields what
they thought were the greatest mysteries today, and then we added a few
that were on our minds, too. This article is one of 15 in LiveScience's
"Greatest Mysteries" series running each weekday.

Shakespeare, hip hop, airplanes and millions of other innovations
are all products of one of mankind's most distinguishing
characteristics: human culture.

While it's clear that our brains hold a remarkable capacity to think
and create, other animals demonstrate what some consider cultural
behaviors. How the astounding complexity and diversity of human
cultures sprang from the much simpler traditions found in animal
communities has remained a puzzle.

"We really know very, very little about the kind of roots of
culture, and the biological origins of culture, and how the forms of
culture we see in our species are similar to or different from those
seen in animals," said zoologist Alex Thornton of Cambridge University.

Much research has focused on the ingredients of human cultural
evolution and other studies have sought to sort out the presence of
simple animal traditions. "What's really lacking is an understanding of
how the two relate to each other," Thornton added.

What is culture?

One of the problems inherent in answering this question is how to define culture.

Anthropologists use a fairly specific definition that requires the use of symbols to transmit cultural knowledge.

"If you define culture according to that, then culture is necessarily something that you find only in humans," Thornton said.

But biologists and animal behaviorists tend to define culture and
tradition as any behavior that is learned by observing or interacting
with others, Thornton said.

Taking this broad definition, some argue that simple traditions can
be seen in animals like guppies, which will follow each other to a food
source, so that a particular path to that source becomes a "tradition"
in that guppy community.

So instead of looking at culture as something that humans came up
with in the last million years or so, as some anthropologists do,
biologists, particularly primatologists "think it's probably much older
than that," said Frans de Waal of the Yerkes National Primate Research
Center in Atlanta. "We basically perfected a system that already
existed."

So if the foundation for the capacity for culture is rooted in our
biology, Thornton argues, one of the ways to find these roots is to
study the simpler traditions seen in other animals.

Clues in our cousins

One of the clearest places to look for clues of our cultural
capacity is in one of our closest relatives: chimpanzees. Researchers
have observed chimps performing certain behaviors that differ between
populations and that seem to be passed by social learning, just as they
are in human cultures.

For instance, some chimp populations have invented a means of
cracking open a nutritious but hard-shelled nut, while other
communities haven't.

The problem with this analogy is that researchers aren't certain
that these traditions are really learned by observing others. They
could be learned individually or could vary with environmental
influences.

"So it's not totally clear that these are actually traditions, and
we need to do experiments to really tease that out," Thornton told
LiveScience.

These are exactly the kinds of experiments de Waal is conducting at
Yerkes, where researchers teach one chimp a skill and watch as it is
disseminated to the other members of the group, showing that chimps can
learn by observing others and spread a behavior through a population.

Thornton cautions though, that "what an animal can do in the lab does not necessarily reflect what it does do in the wild."

The missing link is how intelligence and language—exclusively human
characteristics—played a role in moving us from the simpler traditions
seen in animals to the incredibly complex cultures seen in humans.

Accounting for complexity

One aspect of human culture that makes it so complex is that it is
cumulative, as people build on the inventions of past generations.

"We adapt now culturally to an extent that's unparalleled in any
other creature," said anthropolgist Jon Marks of the University of
North Carolina at Charlotte. As a human product, technology evolves
separately from human biology. (For example, you don't need to talk
about the biology of the makers to discuss the evolution of the
airplane.)

De Waal says that chimps might actually have the capacity for
cumulative traditions. Nut-cracking, for example, is a complex skill
that involves placing a nut between an anvil stone and a hammer stone
and coordinating the movements to hit the nut just right.

"It's unlikely that some chimp all of a sudden did all these things
at the same time, and probably they must have started with something
simpler," he said.

But one of the biggest differences between human and animal culture
is "the fact that we have language and writing, and we can record our
cultures and transmit them in that way," Thornton said.

Language allows us to talk about abstract ideas such as happiness or
love, about the past and the future, and to combine words to express an
infinite variety of ideas. The forms of communication that animals use
are much more limited—they can express a desire to mate, or warn of the
approach of a predator, but those calls cannot be combined to mean
something new.

To trace the exact effects of language and intelligence on the
development of human culture will require a multi-disciplinary effort
examining ancient human cultures, animals in the wild, human psychology
and many other areas of science, Thornton said.

Andrea Thompson

Andrea graduated from Georgia Tech with a B.S. in Earth and Atmospheric Sciences in 2004 and a Master's in the same subject in 2006. She attended the Science, Health and Environmental Reporting Program at New York University and graduated with a Master of Arts in 2006.